The Lantern Gears of Fourfold Memory

The chamber is circular and cramped, its walls ribbed with black stone and inset with brass veins that throb softly like a clock's pulse. A lantern on an overhead arm swings in a steady arc, and every time its light passes over the floor, numbers flare in tarnished gold before sinking back into shadow. A bronze door at the far side clicks once every few seconds, as if counting down to something patient and expensive. The air smells of oil, hot dust, and old rainwater trapped in gears. When the room is worked correctly, the door answers with a clean series of mechanical chimes; when it is not, hidden pistons snap, the lantern stutters, and the whole chamber shivers as if remembering a failed routine.